As I've noted on my profile, I take a ton of pictures, mostly of insects and wildlife. The National Audubon Society Field Guide to North American Reptiles and Amphibians is my go-to resource when I feel the need to identify something of a creepy, crawly nature.
The book is jam-packed with photos of snakes, frogs, and other scaly critters. In fact, the shear amount of images can be a little overwhelming when you're trying to narrow down the possible species of that frog that just jumped into the water and nearly scared the crap out of you.
Another big plus is that the habitats and range of the particular species are mentioned. There have been a few times when I was trying to identify a snake and though "No, they don't come any farther north than Alabama. Better keep looking."
If I had to pick something to gripe about, it would be that I wish this book would fit in a normal-sized pants pocket. It's kind of fat. Other that that, it's a pretty sweet book.